<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>我的文件</title>
    <style>
        div{
            width: 200px;
            height: 100px;
            background-color: red;
            margin: 30px auto;
            border-radius: 10px;
        }
    </style>
</head>
<body>
<div></div>
<div></div>
<div></div>
<div></div>
<section>
    <div>
        <p>
            <b>我是b标签</b>
        </p>
    </div>
</section>
</body>
</html>